Recent studies have demonstrated the presence of several viruses in human atherosclerotic plaques, implicating that clonal proliferation of cells in atherosclerosis may be a result of viral infection of arterial smooth muscle cells. Further, we have obtained preliminary data indicating that dramatic changes are displayed in the genotype and phenotype of clonal lines of SV40 virus-transformed rabbit arterial smooth muscle cells. In this proposal, we plan to transform arterial smooth muscle cells of several mammalian species with SV40 and herpes simplex viruses and then determine if viral transformants express properties typical of arterial plaque cells. For transformation, we will use wild type laboratory strains of viruses, temperature sensitive mutants, and specific virus genome fragments. Clonal lines of viral transformants will be characterized for morphology, smooth muscle cell antigenic markers, viral antigens, levels of ploidy and karyotype, saturation density and anchorage-independent growth. The effect of known growth factors and growth inhibitors on the proliferation of transformed smooth muscle cells will be examined. The extracellular matrix components synthesized by the transformed arterial smooth muscle cells will also be analyzed to determine if transformed clones alter their production of these important cellular proteins. Finally, studies will be conducted to examine whether the LDL receptor pathway functions normally in transformed smooth muscle cells or whether receptors for lipoproteins (B-VLDL, acetylated LDL) can be expressed in transformed smooth muscle cells which are not normally expressed on uninfected smooth muscle cells. These proposed studies on the viral transformation of arterial smooth muscle cells may well demonstrate that the virus-transformed cells develop phenotypic properties comparable to those of plaque cells in atherosclerotic lesions.